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Cormorants: Wildlife Management North and South of the Border

Published 01/25/11
By Barry Kent MacKay, Senior Program Associate

(Photo by Jeff Jones)

Wildlife managers in Canada and the United States both seek to find reasons to kill cormorants in response to pressure from the concerns of sport and commercial fishers who believe that cormorants eat too many fish. In the United States particularly but also in Canada there are the additional concerns of aquaculturists (fish farmers), primarily in the southern States, about cormorants and other piscivorous birds eating their stocks.

There is, however, a distinct difference between the primary reasons wildlife managers give for killing cormorants in Canada from those rationales employed by wildlife managers in the United States to justify slaughtering these magnificent birds. Omitting, for the moment, the specific issue of cormorant depredation of freshwater fish farms that are primarily located in the southeastern United States (often on land degraded by many generations of relatively homogeneous crop production), the difference is this: In Canada the arguments were once the same as in the United States, but that has changed.

At first the concern voiced by wildlife managers in Canada was that the birds were consuming too many fish of the species desired by commercial fishers and sport anglers. But the science clearly did not support the allegation and the focus shifted to concerns that the cormorants, if they weren’t eating enough fish of economic value to the commercial and sport fisheries to justify mass culls, must be eating too many of the fish those fish ate — the “forage fish” who are too small to interest the fishing industry but who are essential parts of the food chain that supports the larger species who are of “sporting” or economic value.

Even that argument faltered, though, under the weight of scientific scrutiny. It’s true that, in Canada no less than in the United States, the antipathy directed by a very vocal part of the public toward cormorants is primarily based on fears that the birds are depriving professional and sport fishers of “their” fish. However, wildlife managers and the more knowledgeable of those lobbying against cormorants know the argument has limited, if any, validity outside of a few exceptional circumstances. Thus they seek to demonize cormorants in other ways, primarily as a threat to the environment and to endangered species.

In the United States, on the other hand, the argument is still primarily that cormorants are depriving anglers of the larger walleyes, bass and other freshwater fish species human anglers covet for themselves.

We will address the arguments in some detail, but, put simply, it should be understood that in a naturally evolved predator-prey relationship it is the prey who determines the population size of the predator, not the other way around.

Looked at another way, if one sees a large number of feeding or breeding cormorants in their natural wetland habitat, it is because there are a great many of whatever it is that they are eating, and that means fish, whatever the species. What they are eating, in terms of species, is of less importance than the knowledge that whatever it is, it is abundant, or the cormorants would not be there in such numbers.

The only exception to this generalization is a contrived circumstance or, on a temporary basis, some form of natural or constructed impoundment, such as a small bay, or the area adjoining a dam or a lake or large pond. And then we’d be talking about only transient (migrating) cormorants, who can eat and fly to another food source. Breeding cormorants don’t have that option, as they must stay within proximity of their dependent young.

Loons, grebes, ospreys, mergansers and other diving ducks, pelicans, kingfishers, ospreys, herons, otters, various species of seals, sea lions, whales and even the endangered Mediterranean monk seal have been, or still are, targeted for elimination for eating “too many” fish in various parts of the world. This antipathy toward animals that consume fish is driven by the same mindset that once saw wolves, hawks, owls and other predators persecuted, in some cases exterminated, as competitors for “game” species. While enlightened hunters, the general public and wildlife managers increasingly understand that predators play important roles within the ecosystem, many of their peers still do not, and among fishermen the situation is worse.

Virtually all fish-eating species of wildlife have, in past eras, felt the wrath of the fishing industry. Some have been exonerated. The Ontario Federation of Anglers and Hunters, which leads the charge against cormorants in Ontario, actually uses an image of the common loon as its logo, apparently not knowing or not caring that it, too, was once culled as a competitor with anglers (and in some instances, still is). Fishermen in Florida can even look fondly at the local brown pelicans as fellow fishers and toss them the odd finny snack. While the occasional osprey is still shot, the species is protected and some communities, although catering to sport anglers or commercial fishers, will even provide nesting platforms for them and seek to protect them from high power lines and other threats.

But the double-crested cormorant is still vilified, and government agents react by killing cormorants.

Introduction: Why Cormorants Can't Kill All Fish

NEXT » Energy Transference, Basic Physics and the Technology Prosthesis

Back in the Real World

Cormorants: Food Chains and Basic Ecological Principles

The Alewife, Alien Salmon and Trout, and the Double-Crested Cormorant

The Round Goby

The Difference Between Science and Management

The Agricultural Subsidy

The Missing Predator Argument

Limiting Factors

Semi-Science and Wildlife Management

So ... What Do Real Scientists Say?

Footnotes

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